The present invention relates to a light transmitter, particularly, to a light transmitter provided with a light guide comprising an optical fiber flux.
As shown in FIG. 1, for example, a conventional light transmitter provided with a light guide comprising an optical fiber flux is used as an illumination optical system of an endoscope. In FIG. 1, light from a light source, 2 such as a lamp, in a light device 1 is applied to a light guide 3 directly or by being reflected by a reflector 2a and is transmitted through the light guide 3 to illuminate an object 4 to be observed. The illuminated object 4 is observed through an observation optical system comprising an objective lens 5, an image guide 6 and an eyepiece 7. However, the light distribution characteristic of the light source 2 varies with the type of light source 2. As shown in FIG. 2, the light distribution curve has a shape forming a trough at an angle of 0.degree. and crests at angles of A.degree. and -A.degree., having values .+-.10.degree. to 20.degree., respectively. With the use of light source 2, light which emerges from the light guide 3 has a light distribution curve similar to the above shape, is dark at the central portion of a view field of an endoscope and results in uneven in illumination. To overcome this problem, as shown in FIG. 3, the light incident end plane 3a of the light guide 3 is obliquely cut. However, the filament image of the light source 2 forms adjacent to the light incident end plane 3a of the light guide 3 and causes sunburn on the high incident end plane 3a. In addition, it is extremely difficult to grind the oblique light incident end plane 3a of the light guide 3 compared to a plane such as a prism.